New data on the cognitive capacities of other primates requires a reevaluation of our position on the nature of human language and the factors that led to its development. Pressures on the limited display system of the social primates may have made changes in the vocal tract anatomy of man associated with the development of upright posture of great selective importance. Human vocal tract anatomy may be at least as important as brain capacity in accounting for the origins of human language. An apparent upper age limit on efficient language acquisition in man leads to the “foreign accent” phenomenon. This may have been adoptively significant as a device which helped in the maintenance of a population structure in which rapid genetic change was possible. Embedding in language may represent a cognitive ability that is also reflected in the capacity for cultural variation, and may be extremely important in maintaining efficient population structure and in selecting for increasing intelligence.